Historically overbased calcium sulfonates have been prepared by reacting a sulfonic acid with calcium hydroxide and carbon dioxide. This process generates a great amount of water. Removing the water extends the processing time, causes the overbased sulfonate to be viscous and generates water waste stream which must be treated before discharging to a sewer. These problems are, ameliorated, if not eliminated, by utilizing calcium oxide and a less than stoichiometric amount of water in place of calcium hydroxide.
U.S. Pat. No. 3,384,587 (Holst et al., May 21, 1968) relates to a method of preparing hyperbasic calcium sulfonate lube oil concentrate useful as detergent dispersant additive in oils comprising forming a first reaction mixture of sulfonic acid or salt thereof, calcium hydroxide or calcium oxide and water, lower alkanol or lower alkoxy ethanol, and lubricating oil, sequentially injecting hydrogen sulfide and carbon dioxide under a hydrogen sulfide and carbon dioxide pressure of at least 10 p.s.i.g. and stipping off incidental water and oxygenated vehicle.
U.S. Pat. No. 3,471,403 (LeSuer et al., Oct. 7, 1969) discloses metal carboxylate complexes that are obtained by treating an oil-soluble carboxylic acid with a metal base in the presence of an acidic gas and an alcoholic promoter. The complexes are useful as detergent additives in fuels, oils, and other organic compositions and are especially useful in lubricating compositions.
U.S. Pat. No. 4,086,170 (De Clippeleir et al., Apr. 25, 1978) relates to calcium sulfonates and concentrated oily solutions thereof that are prepared by reacting a solution of alkylbenzene sulfonic acids with an excess of a calcium oxide having a medium or low activity towards water and with carbon dioxide. Oily solutions of overbased calcium sulfonate obtained from such a calcium oxide are limpid and filterable.
U.S. Pat. No. 4,604,219 (Whittle, Aug. 5, 1986) is directed to alkaline earth calcium sulfonates that are derived from natural or synthetic feedstocks or a mixture of both which can be overbased by introducing into a mixture comprising a neutral alkaline earth calcium sulfonate, a lower alcohol, a light hydrocarbon diluent carbon dioxide and water. The water is introduced continuously and at a uniform rate over 1-4 hours, preferably 1-3 hours into the heated mixture with carbon dioxide. Water is added in a molar ratio water/calcium oxide of 0.1 to 1.2 preferably 0.4 to 0.8. It has been found that both the water rate and amount are critical. It has been unexpectedly found that a superior product is formed by adding water continuously during carbonation rather than all charged in one or several increments at the beginning of the carbonation. In this reference, a high calcium sulfonate product with improved filterability and high clarity is formed with good line utilization.
U.S. Pat. No. 4,775,490 (Nichols et al., Oct. 4, 1988) describes a process for overbasing a substrate comprising mixing the substrate, water, a phenol, a source of magnesium and a carbonating agent, wherein the water is retained throughout the overbasing reaction and provided further that the weight ratio of the water to the magnesium is in a 10:1 to 1:5 weight, ratio, thereby obtaining a magnesium overbased substrate.
U.S. Pat. No. 4,954,272 (Jao, et al., Sep. 4, 1990) is directed to a process for producing an overbased oil soluble calcium sulfonate having a TBN of 325, said process comprising:
(a) diluting a neutral calcium sulfonate with a hydrocarbon solvent and a lower alkanol; PA1 (b) adding to the diluted calcium sulfonate solution, CaO, Ca(OH).sub.2 and H.sub.2 O in molar ratios of CaO:Ca(OH).sub.2 of about 90:10 to about 20:80 and of H.sub.2 O:CaO of about 0.15:1 to about 0.30:1; PA1 (c) heating the sulfonate mixture to a temperature ranging from about 100.degree. F. to about 170.degree. F. under a pressure ranging from about 0 to about 50 p.s.i.g.; PA1 (d) passing CO.sub.2 into the heated sulfonate mixture for a period of about 50 to about 200 minutes; PA1 (e) adding a diluent oil to the CO.sub.2 treated sulfonate mixture; PA1 (f) separating the solids from the liquid of the sulfonate mixture; and PA1 (g) stripping the hydrocarbon solvent from the resulting overbased oil soluble sulfonate product having TBN of 325. PA1 (a) an oil-soluble acid material; PA1 (b) a promoter comprising: PA1 (c) greater than 1 equivalent of a calcium base per equivalent of oil-soluble acid material. PA1 (a) mixing a substrate comprising a sulfonic acid or a calcium salt of a sulfonic acid, with at least one alcohol, a diluent oil, a carboxylic acid, an acidic material, water and calcium oxide to form a mixture; PA1 (b) heating the mixture to its reflux point to form a neutral calcium salt of the acid moieties; PA1 (c) removing a substantial portion of distillable solvents to form an intermediate residue; PA1 (d) adding to the intermediate residue at least one alcohol, a surfactant, calcium oxide and water such that for every 100 parts of substrate, there are not more than 25 parts water to form an intimate mixture having a direct base number of 90-250; PA1 (e) heating said intimate mixture (d) to below its reflux point to form a heated intimate mixture; PA1 (f) passing gaseous carbon dioxide into the heated intimate mixture (e) to form an overbased calcium sulfonate and a mixture of calcium hydroxide, calcium carbonate and regenerated water until the direct base number is from 90-150; PA1 (g) adding additional calcium oxide until the direct base number is from 90-250 followed by the passing of additional gaseous carbon dioxide until the direct base number is from 90-150; PA1 (h) continuing the passing of gaseous carbon dioxide to a direct base number of 0-75 after the last portion of calcium oxide is added; PA1 (i) removing any distillable solvents to form a final residue; and PA1 (j) filtering the final residue to obtain a substantially solvent-free and solids-free oil soluble overbased calcium sulfonate; PA1 with the proviso that calcium oxide is the only substantial source of overbasing calcium.
U.S. Pat. No. 5,259,966 (Burke, Jr., et al., Nov. 9, 1993) provides a process for preparing an overbased calcium salt, comprising mixing together:
(i) an alcohol or alcohol mixture, and PA2 (ii) an inorganic calcium salt other than chloride which is soluble in the alcohol mixture of (i), or an acid or salt which forms said inorganic calcium salt when treated with a calcium base; and
U.S. Pat. No. 5,534,168 (Cleverley et al., Jul. 9, 1996) relates to the use of magnesium oxide of specified, low, reactivity in a process for the production of overbased magnesium sulfonates, together with the introduction of water and an alcohol, into the reaction mixture during carbonation, makes it possible to prepare high base number products which have very low post carbonation sediments and which can be purified by rapid filtration.